Metal chair joint



Oct. 25, 1955 J. A. FITCH 2,721,606

METAL CHAIR JOINT Filed Dec. 22, 1953 2 Sheets-Sheet 1 J J1? Z 40\ /9 /9- 40 r1 r1 1 42 42 i i 2.9 i I /4 a i l'0 d gj' tii I /4 46 33 /6 /6 29 INVENTOR. 3/ dAso/v A. FITCH camaflawvam,

ATTORNEYS.

Oct. 25, 1955 J c 2,721,606

METAL CHAIR JOINT Filed D60. 22, 1953 2 Sheets-Sheet 2 INVENTOR. dAsoA/A. F/TCH BY @64 4, mraem ATTORNEYS.

United States Patent METAL CHAR! JOINT Jason A. Fitch, Lakewood, N. Y., assignor to Art Metal Construction Company, Jamestown, N. Y.

Application December 22, 1953, Serial No. 3%,652

7 Claims. (Cl. 155-196) This invention relates to metal chair constructions, and more particularly to improvements in back-to-seat joint constructions in metal furniture such as office chairs and the like.

One of the objects of the invention is to provide a metal furniture joint as aforesaid which is of improved rigidity and strength under service stresses.

Another object of the invention is to provide an improved metal furniture joint as aforesaid comprising certain standard parts and novel reinforcement devices such as are inexpensive to manufacture and assemble.

Another object of the invention is to provide a novel and improved chair joint reinforcement device which is inexpensively manufactured and adapted to be readily interchangeable between right and left hand side joints of a chair construction. Other objects and advantages of the invention will appear in the specification hereinafter.

In the drawings:

Fig. 1 is a fragmentary front perspective view of a metal chair seat and back frame construction incorporating right and left side seat-to-back joint reinforcement arrangements of the present invention;

Fig. 2 is a fragmentary horizontal section taken along line IIII of Fig. 3, on an enlarged scale, through the left side joint construction of Fig. 1;

Fig. 3 is a fragmentary vertical section taken along line III-III of Fig. 2;

Fig. 4 is an elevation of one of the joint reinforcement elements of the invention, as initially blanked out prior to bending into final form; and

Fig. 5 is a view like Fig. 4 of the other reinforcement element, also shown as initially blanked out prior to bending thereof into final form.

In the drawing, the invention is illustrated as being embodied in an oflice chair construction including generally a seat frame comprising a channel sectioned metal fabrication including a side wall structure 12 and top and bottom flanges 14-16, respectively. The seat frame structure 10 may of course be fabricated by any suitable bending and welding operations or the like, as is well known in the art. As shown in the drawing, the back frame construction of the chair includes a pair of vertically disposed back-leg members designated generally at 18-18 which may be conveniently provided in the form of square tubing metal stock pieces, each having a front wall portion 19; opposite side wall portions 20-20; and a rear wall portion 21; whereby the back frame members 18-18 are of box sectional form as shown for example in Fig. 2.

Whereas, such seat frame and back frame structures have been previously interconnected by simple bolt and nut or machine screw connection devices or the like, it has been determined that such methods of interconnection are deficient in that they do not provide permanently rigid connections between the seat frame and seat-back parts under normal usage conditions. In accord with the present invention the disadvantages and difiiculties of the prior art are overcome by providing, in combination with the seat frame and back frame parts as aforesaid an improved joint reinforcement device. Such devices comprise, in the case of each joint, a pair of novelly shaped joint reinforcement brackets as illustrated at 24-25 in the drawing. The devices 24-25 are generally of anglebracket form cut out of metal plate stock and bent to comprise leg portions extending in angularly diverse directions whereby the leg portions of the bracket devices complement the angularities of the corresponding rear corner constructions of the seat frame. Thus, the brackets are adapted to nest into the rear corner portions of the channel sectioned seat frame member 10, as illustrated in the drawing.

More specifically, as shown in Figs. 4 and 5, the brackets 24-25 are first blanked out of plate metal stock in generally similar flat strip form before being bent angularly as shown in Figs. 1-2; but the blank for the bracket 24 is recessed as indicated at 28 (Fig. 4) along its upper edge portion, and is provided with a downwardly extending tab portion 29 and an upwardly recessed portion 30 at its bottom edge portion. The blank for the bracket 25 is formed with a substantially centrally located recessed portion 31 at its bottom edge, and a short recessed portion 32, and an upwardly extending tab portion 33 at its upper edge. The blanks for the brackets 24-25, after having been struck out of flat metal plate into the forms illustrated in Figs. 45, are bent at their mid-portions as indicated at 34-35 into appropriately angled bracket forms so as to be then adapted to nest in pairs into the corner portions of the seat frame structure, as explained hereinabove; and the tab and recessed portions 29-30 of the back member 24 are so dimensioned and arranged as to be adapted to mate with the recess and tab portions 32-33 of the bracket 25 when the bracket devices are assembled in the nested position in the corner portions of the seat frame, as shown in Fig. l.

The brackets 24-25 are suitably apertured as indicated' at 36-37 and 38-39, respectively, to receive in slip-fitting relation therethrough the shank portions of machine screws 42 for anchoring the bracket devices 24-25 in firmly nested relation in the corner portions of the seat frame incidental to connections of the seat frame corner portions to the corresponding back frame mem bers 18-18, as shown in Figs. 1 to 3. To enhance the rigidity and strength of the screw connections between the seat frame and the back frame elements, a reinforcing member of flat metal bar stock as indicated at 40 is slip-fitted inside each tubing piece 18 and is drilled and tapped in line with the apertures formed in the bracket members 24-25 so as to be adapted to receive in screwthreaded relation the threaded shank portions of the screws 42 when the chair construction is assembled.

Thus, it will be appreciated that the chair parts hereinabove described and illustrated may be easily assembled by first slip-fitting the frame and bracket and reinforcement parts into the positions shown in the drawings, whereupon sinking of the screws 40 into securing positions as shown in Figs. l-3 will operate to draw the chair construction parts together in snugly nested form, in such manner that the relatively thin-sectioned seat frame and back frame members will be thereby clamped firmly together under compression between the relatively thicksectioned corner bracket and reinforcement plate devices which in turn are drawn and locked together by means of the machine screws 40.

It is a particular feature of the present invention that the bracket devices 24-25 are vertically dimensioned so that when they are arranged in pairs as illustrated in the drawing in mating relationship, and assembled interiorly of the seat frame member 10, the upper and lower edges of the assembled bracket unit will fit snugly upwardly and downwardly against the top and bottom flange portions 1416 of the seat frame member 1i). Thus, when in this assembled relationship, the paired bracket devices 24 25 are integrated so as to function as single bracket devices of vertical dimensions commensurate with the internal vertical dimensions of the seat frame member between the upper and lower flanges 1416 thereof.

The top and bottom flange portions 1416 of the seat frame structure are preferably provided with inturned marginal edge portions as indicated at 46-47 for reinforcement purposes (Fig. 3), but the bracket devices 24-25 may nevertheless be easily inserted into operative positions as shown in the drawing and then arranged in mating unitary relation in nested position in the corners of the seat frame; whereas one piece brackets of similar full height could not be so slip-fitted into position. Furthermore, it is a particular feature of the present invention that the mating recess and tab portions 3229 and 33 of the brackets 2425 are formed with sloping end portions as shown in the drawing, whereby when the finished chair is subjected to normal service stresses such as tend to lever the top of the chair-back forwardly or rearwardly relative to its normal attitude with respect to the chair frame, the forces in the joints tend to relatively displace the brackets 2425 longitudinally with respect to one another. Such relative movements of the brackets 2425 initiate camming actions between the mating sloping end portions of the tab and recess portions of the bracket members, thereby tending to vertically expand or increase the vertical dimension of the bracket units which are nested within the corners of the seat frame structure. Thus, the upper and lower edges of the bracket devices are forced still more firmly against the curved top and bottom flange portions 1416 of the C-sectioned seat frame member 10 to resist any such relative movements between the bracket members; whereby the seat frame and back frame members are relatively braced against angular motions in superior manner.

It is another particular feature of the present invention that whereas the bracket members 24-25 are each provided with opposite apertures 3637 and 38-39, respectively, they are thereby suited to use either in the left hand or right hand corner constructions of the chair as shown. For example, as shown in Fig. l, a pair of the brackets are nested in the left hand corner construction and connected thereto through the apertures 37, 39; while a pair of similar brackets are arranged in upside-down relation in the right hand corner construction and connected thereto through the apertures 36, 38 thereof. Thus, the bracket devices are readily interchangeable, and easily assembled as explained hereinabove and then drawn into firm locking positions in the chair corners to reinforce the corner constructions in improved manner.

Whereas, only one form of the invention has been shown and described in detail, it will be apparent to those skilled in the art that the invention is not so limited but that various changes may be made therein without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In a metal chair frame including a hollow leg member formed of relatively thin sectioned metal and a seat frame member of relatively thin metal, said seat frame member being of C-sectioned form and disposed flatwise against said leg member for joint connection therewith, said leg and seat frame members being apertured in alignment to receive a pair of screws in slip-fitted relation therethrough, a leg reinforcement bar comprising a metal piece slip-fitted inside said leg member and drilled and tapped in alignment with said screw devices for screwthreaded connections therewith, and a pair of joint reinforcement brackets of angular form dimensioned and arranged so as to nest inside of said frame member at the corner joint portion thereof, said brackets being apertured in alignment with said previously mentioned apertures,

CPI

said screws being slip-fitted through said apertures and headed at their outer ends so as to bear against said brackets when engaged in a screwthreaded relation with said reinforcing bar thereby drawing the assembly together in firmly locked condition, said brackets having complementing recess and extending tab portions respectively, each formed with sloping side portions arranged in mating relation whereby camming forces tending to longitudinally displace said brackets relative to one another tend to spread said bracket members apart against the confinements of the opposite flange portions of said C-shaped frame member.

2. In a metal chair frame including a leg member of enclosing wall form and a seat frame member, said seat 'rame member being of channel-sectioned form and disposed flatwise against said leg member for joint connection therewith, said leg and seat frame members being apertured in alignment to receive a pair of screws in slipfitted relation therethrough, a leg reinforcement bar com prising a metal piece slip-fitted inside the enclosing walls of said leg member and drilled and tapped in alignment with said screw devices for screwthreaded connections therewith, and a pair of joint reinforcement brackets of angular form dimensioned and arranged so as to nest inside of said channel sectioned frame member at the corner joint portion thereof, said brackets being apertured in alignment with said previously mentioned apertures, said screws bein slip-fitted through said apertures and headed at their outer ends so as to bear against said brackets when engaged in a screwthreaded relation with said reinforcing bar thereby drawing the assembly together in firmly locked condition, said brackets having complementing recess and extending tab portions respectively, each formed with sloping end portions and arranged in mating relation whereby camming forces tending to longitudinally displace said brackets relative to one another tend to spread said bracket members apart against the confinements of the opposite flange portions of said channel sectioned frame member.

3. In a metal chair frame including a leg member and a seat frame member, said seat frame member being of channel-sectioned form and disposed flatwise against said leg member for joint connection therewith, said leg and seat frame members being apertured to receive screws in connecting relation therethrough, and a pair of joint reinforcement brackets of angular form dimensioned and arranged so as to nest inside of said frame member at the corner joint portion thereof, said screws being fitted through said brackets and engaged in screwthreaded relation with said leg member thereby drawing the assembly together in firmly locked condition, said brackets having complementing recess and tab portions respectively, each formed with sloping side portions arranged in mating relation whereby camming forces tending to longitudinally displace said brackets relative to one another tend to spread said bracket members apart against the confinements of the opposite flange portions of said channel sectioned frame member.

4. In a metal chair frame including a box-sectioned leg member of relatively thin metal wall form and a seat frame member, said seat frame member being of C-sectioned metal form and disposed flatwise against said leg member for joint connection therewith, said leg and seat frame members being apertured in alignment to receive a pair of screws in slip-fitted relation therethrough, a leg reinforcement bar comprising a metal piece slip-fitted inside leg member and drilled and tapped in alignment with said screw devices for screwthreaded connections therewith, and a plurality of joint reinforcement brackets of angular form dimensioned and arranged so as to nest as a unit when stacked inside of said C-shaped frame member at the corner joint portion thereof, said brackets being aperturned in alignment with said previously mentioned apertures, said screws being slip-fitted through said apertures and headed at their outer ends so as to bear against said brackets when engaged in a screwthreaded relation with said reinforcing bar thereby drawing the assembly together in firmly locked condition, said brackets having complementing recess and tab portions respectively, each formed with sloping side portions and arranged in mating relation whereby camming forces tending to longitudinally displace said brackets relative to one another tend to spread said bracket members apart against the confinements of the opposite flange portions of said C-shaped member.

5 In a metal chair frame including a hollow leg member of relatively thin sectioned metal form and a seat frame member of relatively thin metal, said seat frame member being of channel sectioned form and disposed flatwise against said leg member for joint connection therewith, said leg and seat frame members being apertured in alignment to receive a pair of screws in slip-fitted relation therethrough, a leg reinforcement bar comprising a metal piece fitted inside said leg member and drilled and tapped in alignment with said screw devices for screwthreaded connections therewith, and a pair of joint reinforcement brackets dimensioned and arranged so as to nest inside of said frame member at the corner joint portion thereof, said brackets being apertured in alignment with said previously mentioned apertures, said screws being slip-fitted through said apertures and headed at their outer ends so as to bear against said brackets when engaged in a screwthreaded relation with said reinforcing bar thereby drawing the assembly together in firmly locked condition, said brackets having complementing recess and extending tab portions respectively formed with contiguous sloping side portions arranged in mating relation whereby camming faces tending to longitudinally displace said brackets relative to one another tend to spread said bracket members apart against the confinements of the opposite flange portions of said channel sectioned frame member.

6. In a metal chair frame including a hollow leg member and a seat frame member, said seat frame member being of channel sectioned form and disposed flatwise against said leg member for joint connection therewith, said leg and seat frame members being apertured in alignment to receive a pair of screws in slip-fitted relation therethrough, a leg reinforcement bar comprising a metal piece slip-fitted inside said leg member and drilled and tapped in alignment with said screw devices for screwthreaded connections therewith, and a pair of joint reinforcement brackets of angular form dimensioned and arranged so as to nest inside of said channel sectioned frame member at the corner joint portion thereof, said brackets being apertured in alignment with said previously mentioned apertures, said screws being slip-fitted through said apertures and headed at their outer ends so as to bear against said brackets when engaged in a screwthreaded relation with said reinforcing bar thereby drawing the assembly together in firmly locked condition, said brackets having complementing recess and extending tab portions respectively formed with contiguous oppositely inclined side portions whereby camming forces tending to longi tudinally displace said brackets relative to one another tend to spread said bracket members apart against the confinements of the opposite flange portions of said channel sectioned frame member.

7. In a metal chair frame including a leg member and a seat frame member, said seat frame member being of channel sectioned form and disposed against said leg member for joint connection therewith, said leg and seat frame members being apertured to receive screws in connecting relation therethrough, and a pair of joint reinforcement brackets of angular form dimensioned and arranged so as to nest inside of said frame member at the corner joint portion thereof, said screws being fitted through said brackets and engaged in screwthreaded relation with said leg member thereby drawing the assembly together in firmly locked condition, said brackets having complementing recess and tab portions respectively formed with oppositely inclined contiguous side portions whereby camming forces tending to longitudinally displace said brackets relative to one another tend to spread said bracket members apart against the confinements of the opposite flange portions of said channel sectioned frame member.

References Cited in the file of this patent UNITED STATES PATENTS 426,231 Bosworth Apr. 22, 1890 1,770,722 Wright July 15, 1930 2,480,183 Dewey Aug. 30, 1949 2,632,535 Clerk Mar. 24, 1953 

